/*
 * Copyright 2016 Google Inc.
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */

#ifndef SKSL_SWIZZLE
#define SKSL_SWIZZLE

#include "include/core/SkTypes.h"
#include "src/sksl/SkSLDefines.h"
#include "src/sksl/SkSLPosition.h"
#include "src/sksl/ir/SkSLExpression.h"
#include "src/sksl/ir/SkSLIRNode.h"
#include "src/sksl/ir/SkSLType.h"

#include <cstdint>
#include <memory>
#include <string>
#include <string_view>
#include <utility>

namespace SkSL {
class Context;
enum class OperatorPrecedence : uint8_t;

namespace SwizzleComponent {
enum Type : int8_t {
    X = 0,
    Y = 1,
    Z = 2,
    W = 3,
    R = 4,
    G = 5,
    B = 6,
    A = 7,
    S = 8,
    T = 9,
    P = 10,
    Q = 11,
    UL = 12,
    UT = 13,
    UR = 14,
    UB = 15,
    ZERO,
    ONE
};
} // namespace SwizzleComponent

/* *
 * Represents a vector swizzle operation such as 'float3(1, 2, 3).zyx'.
 */
class Swizzle final : public Expression {
public:
    inline static constexpr Kind kIRNodeKind = Kind::kSwizzle;

    using Component = SwizzleComponent::Type;

    Swizzle(const Context &context, Position pos, std::unique_ptr<Expression> base, const ComponentArray &components)
        : INHERITED(pos, kIRNodeKind, &base->type().componentType().toCompound(context, components.size(), 1)),
          fBase(std::move(base)),
          fComponents(components)
    {
        SkASSERT(this->components().size() >= 1 && this->components().size() <= 4);
    }

    // Swizzle::Convert permits component arrays containing ZERO or ONE, does typechecking, reports
    // errors via ErrorReporter, and returns an expression that combines constructors and native
    // swizzles (comprised solely of X/Y/W/Z).
    static std::unique_ptr<Expression> Convert(const Context &context, Position pos, Position maskPos,
        std::unique_ptr<Expression> base, ComponentArray inComponents);

    static std::unique_ptr<Expression> Convert(const Context &context, Position pos, Position maskPos,
        std::unique_ptr<Expression> base, std::string_view maskString);

    // Swizzle::Make does not permit ZERO or ONE in the component array, just X/Y/Z/W; errors are
    // reported via ASSERT.
    static std::unique_ptr<Expression> Make(const Context &context, Position pos, std::unique_ptr<Expression> expr,
        ComponentArray inComponents);

    std::unique_ptr<Expression> &base()
    {
        return fBase;
    }

    const std::unique_ptr<Expression> &base() const
    {
        return fBase;
    }

    const ComponentArray &components() const
    {
        return fComponents;
    }

    std::unique_ptr<Expression> clone(Position pos) const override
    {
        return std::unique_ptr<Expression>(new Swizzle(pos, &this->type(), this->base()->clone(), this->components()));
    }

    std::string description(OperatorPrecedence) const override;

    // Converts an array of swizzle components into a string.
    static std::string MaskString(const ComponentArray &inComponents);

private:
    Swizzle(Position pos, const Type *type, std::unique_ptr<Expression> base, const ComponentArray &components)
        : INHERITED(pos, kIRNodeKind, type), fBase(std::move(base)), fComponents(components)
    {
        SkASSERT(this->components().size() >= 1 && this->components().size() <= 4);
    }

    std::unique_ptr<Expression> fBase;
    ComponentArray fComponents;

    using INHERITED = Expression;
};
} // namespace SkSL

#endif
